An automotive airbag system is a system for protecting a driver or a passenger at the time of collision of an automobile, etc. and is composed of a device for sensing an impact upon collision and an airbag device. The airbag device is mounted on a steering wheel, an instrument panel ahead of a passenger seat, driver and passenger seats, front and side pillars, etc.
With respect to an airbag housing cover in an airbag device, there is a fear that at the time of inflation of an airbag, broken pieces resulting from collapse of a cover housing the airbag may be scattered or the cover may fly apart due to fracture of the cover attachment part. Therefore, for the purpose of preventing the cover from abnormal collapse and scattering, various proposals have been made in terms of the structure or material thereof.
As the material of the airbag housing cover, for example, a material composed of a hydrogenated styrene-conjugated diene block copolymer, a plasticizer for rubber, an olefin-based resin and additives has been proposed in Patent Document 1. In addition, a material composed of a propylene-based resin, an ethylene-α-olefin copolymer and a styrene-based elastomer has been proposed in Patent Documents 2 to 4, and a material composed of an olefin-based elastomer, a propylene-based resin and an ethylene-α-olefin copolymer has been proposed in Patent Document 5. Furthermore, a material composed of a propylene-based resin produced by multistage polymerization and an ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber has been proposed in Patent Document 6.